I realize you were trying to be polite, but you need to report the accident to the police. They will let you know their level of involvement. They may also help determine fault for the accident. After that you need to contact the person whose vehicle you were using - because that insurance will be "primary." Your insurance coverage will be "excess." After that, family friend or not, you will need to reach that person's insurance company. That person's insurance company will be responsible for fixing the vehicle you were driving.